This application relates to a method and kit for use in testing cells, and particularly tumor or leukemia cells, for drug sensitivity.
Chemotherapy agents are frequently employed in treatment of many forms of cancer. The theory underlying the use of these agents, which are all extremely cytotoxic, is that they will be more harmful to the rapidly dividing tumor cells than to the patient as a whole. In some cases, however, a given tumor either proves to be initially resistant to the chemotherapy agents administered or develops resistance over the course of treatment. This resistance, whether natural or induced, cannot be overcome by simply increasing the dosage because this may unacceptably increase the harmful side effects of the agent to the patient, and it therefore becomes necessary to completely change the treatment regime.
The harm to the patient from an aborted attempt at chemotherapy may be substantial. First, the patient has been physically injured to some extent by the administration of the chemotherapy agents and has not received much, if any, offsetting benefit. Second, in many cases, the cancer may progress during the period of ineffective treatment to a point where the therapy with the second-chosen group of agents comes too late to substantially prolong the patient's life. Accordingly, a method of determining the drug sensitivity profile of a given tumor prior to the administration of chemotherapy agents would be highly desirable.
Several tests have been disclosed whose goal is the prediction of resistance to chemotherapy agents. One of the earliest of these was based on the observation in 1954 that the ability of chemotherapy agents to reduce cellular metabolism could be monitored by measuring tetrazolium blue reduction by fresh tumor biopsy materials. (Black et al., J. Nat'l Cancer Inst. 14, 1147-1158 (1954)). Subsequently, assays have been proposed that rely on cloning of human tumor stem cells, (Salmon et al., N. Engl. J. Med. 298, 1321-1327 (1978)), on the uptake of radiolabeled thymidine by tumor cells in the presence and absence of the chemotherapy agent being tested (Kern et al., Int'l J. Cell Cloning 5, 421-431 (1987)); and on the differential staining properties of living and dead cells (Weisenthal et al., Oncology, 5, 93-103, (1991)).
Each of these assays provides a measure of predictability to the question of tumor drug resistance. Many of these assays take 7 to 21 days to complete, however, which in some cases is longer than many physicians are willing to wait before initiating chemotherapy. Furthermore, the reliability of these tests is sufficiently variable that not all physicians are willing to trust the test results. There thus exists an unfulfilled need for a predictive assay for drug resistance which provides rapid, reliable results for a spectrum of possible chemotherapy agents. It is an object of the present invention to provide such an assay.